Samples of poly[1–(trimethylsilyl)–1–propyne] were kept for about 4 years in ambient conditions. The permeability and diffusion coefficients were examined and found to be decreased by 1–2 orders of magnitude. To ascertain the nature of the changes underwent during long‐term storage of this polymer, several physicochemical methods were applied: positron annihilation, wide‐angle X‐ray diffraction, spin probe, and density evaluation. These studies indicated that a decrease of free volume and more close chain packing took place during the aging process. IR spectroscopy and 13C‐NMR showed that oxygen‐containing products appeared in the polymer after long‐term storage. This should result in a certain decrease in the rigidity of the backbone chains and more intensive interchain in‐teractions, and, hence, in a decrease in the free volume of the aged polymer. © 1993 John Wiley & Sons, Inc.

Experimental partPoly(dipropylsiloxane)a) (PDPS) was obtained by anionic polymerization of hexapropylcyclotrisiloxane in the presence of KOH under an argon flux at 115°C. The polymer obtained was fractionated from a toluene/methanol (1 : 99 by vol.) solution at 25 "C. Fractions were taken 24 h after reaching equilibrium conditions. The molecular weights were determined by light scattering in toluene at 25 "C. In our study the fraction with an intrinsic viscosity [q] = 0,26 dl/g in toluene at 25 "C and a weight-average molecular weight M, = 82000 was used. Calorimetric and X-ray studies were carried out on the sample which after fractionation was heated to 500 K and cooled slowly to room temperature.Systematic name: poly(oxydipropylsily1ene).

Abstract:Gold is transported in high-temperature chloride-bearing hydrothermal fluids in the form of AuCl 2 − . The stability of this complex has been extensively studied, but there is still considerable disagreement between available experimental data on the temperature region 300-500 • C. To solve this problem, we measured the solubility of gold in HCl/NaCl fluids (NaCl concentration varied from 0.1 to 3 mol·(kg·H 2 O) −1 ) at 450 • C and pressures from 500 to 1500 bar (1 bar = 10 5 Pa). The experiments were performed using a batch autoclave method at contrasting redox conditions: in reduced experiments hydrogen was added to the autoclave, and in oxidized experiments the redox state was controlled by the aqueous SO 2 /SO 3 buffer. Hydrogen pressure in the autoclaves was measured after the experiments in the reduced system. The gold solubility constant, Au (cr) + HCl • (aq)

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